A Mark‐Recapture Estimate of the Number of American Eels Arriving at the Lowermost Barrier on the Wolastoq|Saint John River, Canada
Bibliographic record
Abstract
ABSTRACT The upstream migration of juvenile American eels ( Anguilla rostrata ) is frequently obstructed by dams and other in‐stream barriers, leading to habitat loss and fragmentation, factors that are believed to contribute to the species' population decline. While fishways can help restore access to upstream habitats, their effective design and implementation require reliable estimates of the number of eels arriving at migration barriers. The Mactaquac Dam and Generating Station (672 MW) is the lowermost barrier on the Wolastoq|Saint John River in Canada and currently does not provide an eel‐specific fish passage. To inform the design and required capacity of a potential future eel passage at this site, this study provides mark‐recapture‐based estimates of the number of American eels arriving in the tailrace during three consecutive upstream migration seasons (2021–2023). During the peak migration period from late June to early August, a total of 30,144 juvenile eels were captured, tagged with visible implant elastomer tags, and released in the spillway bays of the dam over multiple sampling occasions spanning 30 to 42 days. Data were analyzed using POPAN Jolly‐Seber models and resulted in population estimates ranging from approximately 150,000 individuals in 2021 and 2022 to approximately 950,000 in 2023. Although confidence intervals were relatively wide, these results highlight the importance of an upstream passage system for eels at this dam, provide guidance for future research and management, and demonstrate the potential for long‐term monitoring at a future eel ladder to support local stock assessment.
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How this classification was reachedexpand
Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.001 | 0.003 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.001 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.000 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one teacher head, not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".